Try Eclipse OpenJ9 (former IBM) instead of the 'default' JVM, and compare impacts of different settings of them?
( https://en.wikipedia.org/wiki/OpenJ9 )
Maybe jumbo-frames for your LAN, but I wouldn't expect too much from that.
Since you're already running Arch, try including CachyOs's highly optimized repositories, kernel, interesting scheduling options, and endless other goodies?
It's not for gamers only. One doesn't even need to use most of their utilities for noobs, though some are convenient, like switching through schedulers and their settings with a few clicks.
